Quartz seal and method of producing the same



Aug. 15. 1933. E, Q, EmcksoN 1,922,536

QUARTZ SEAL AND METHOD OF PRODUCING THE SARE Original Filed June 16. 1930 Patented Aug. 15, Y 1933 UNITED STATES QUARTZ SEAL AND -METHOD F PRODUC- ING THE SAME Ellis 0. Erickson, Pasadena, Calif.; assignor to Claude Neon Electrical Products Corporation, Ltd., Wilmington, Del., a Corporation of Dela-A Ware Original application June 16, 1930, Serial No. 461,351. Divided and this application January 27, 1933. Serial No. 653,766

4 Claims.

This is a division of my copending application, Serial No. 461,351, led June 16, 1930, for quartz seal and method of producing the same, in which is claimed the method of producing the seal,

5 While this application is particularly directed to the seal which is formed by my method.

' This invention relates to a quartz seal and to a methodl of producing the same. Invarious quartz apparatus, it is desired to pass a metallic wire into the vessel and form an air-tight seal around the wire. Thus, in certain vacuum apparatus, neon tubes, etc., electrodes, filaments, or other parts within the tube are desired to bev provided with a lead line for making electrical connections. It isnecessary that these lead lines be sealed to the quartz with asubstantiallyairtight seal. Since the coefficient of expansion of quartz is so widely diiferent from any metal which can be utilized asA such a lead line conduit, it is extremely diiiicult to effect a nonleaking seal. Also, because of the fact that the quartz requires such a high temperature, i. e. 1700 to 1750"Q. before it can be worked, .diiiiculty is encountered in making a seal without burning the metal. The diflculties of forming the seal are great, and the number of metals suitable for use as a seal are extremely limited.

It is the purpose of the present invention Vto provide a seal for passing a .metal lead line through quartz and a process of producing the same which is satisfactory in practice and simple and economical to use and construct.

Generally considered, the invention comprehends that by providing a very ne diameter wire in a portion of the lead line and over a suihcient length the quartz may be caused to sired nished apparatus.

'seal suiliciently vtight to said wire as to eliminate practically all' leakage. The invention also comprehends a construction and process of construction such as 'aseal which is simpleto carry out and which assures against the metal in this line lead line being vaporized fromand broken during operations of forming a seal into the devThe invention also provides a seal which is formed independently of, and which is separate from, the apparatus into which it is to be nally sealed, and provides avform of seal which may be readily welded in place in the desired appara- 'tus in a simple manner without danger of d estruction of the seal.

The invention also provides a form of seal especially suitablefor-:connecting-the electrodes which the seal is to be made.

tubes made of quartz are of special value as therapeutic lamps.

The present invention, together with various additional objects and advantages, will best be understood from the' description of a preferred form or example of a quartz seal and process of producing the same, embodying the invention. The seal and process are illustrated by reference to the accompanying drawing, in which Figure 1 is a sectional view of a capillary used in forming a seal.

Figure 2 is an illustration of the lead wire utilized inthe seal.

Figure 3 is a seal unit or blank.

Figure 4 is a blank after it is operated upon for attaching an electrode.

Figure' illustrates the seal attached to the electrode.

Figure 6y illustrates the position of the seal and electrode in a tube before the operation of combining the seal with the tube so that the seal may function in the apparatus of which thetube Figure 7 illustrates the seal after it has been welded to the tube. v

Figure 8 illustrates the seal with its outer end removed in order that electrical connections may be made.

Figure 9 is a sectional view of the capillary 'and lead wire assembled and connected to an evacuating pump. Y Referring to the drawing:

In preparing the seal, I prefer to employ a capillary'section 2 having one end 3 witha narrow bore closed at its end. The narrow bore, for example, is preferably one millimeter in diameter. 'I'he narrow bore portion of the capillary connects with a larger 'bore section 4 and then with an enlargement 5 which may serve as a nipple for attaching the capillary to the hose of a vacuum pump.

In Figure 2 there is illustrated a wire which is to form a 'lead to 'an electrical part and with The wire comprises a central portion 6 of a very line diameter which, for example, is .0006 inches in diameter. This wire must be made of metal having a melting point higher than that o i' quartz and preferably of high tensile strength,.and tungsten is the metal I have generally chosen as best for filling these requirements and also being one which is commercially available in this small diameter. The length of the sections of the lead wire should be, suillcient` to insure an adequate leal. Generallyspeaking. the larger the diamelos ' ter, the longer length necessary to insure a seal,

while the smaller the diameter the less length. I have found in practice that with a .0006 inch diameter tungsten wire of 3A inch in length a seal of quartz may be produced which fails to register any leakage. To the ends of this section 6 of wire there should be welded lead lines '7 and 8 of a flexible wire and of larger diameter. The material of the leads to the sealing wire 6 may be varied, but the requirement for the use of a metal'having a melting point higher than that of quartz and also of substantially flexible nature, even after having been subjected to high temperatures at which quartz is worked, has led to the selection of molybdenum. While the diameter of the leads 7 and 8 is not critical, I have, for example, employed molybdenum in .015 Inches in diameter.

In the process of making the seal, the wire shown in Figure 2 is placed within the narrow bore of capillary Z and the capillary 2 is then connected with a hose 9, as shown in Figure 9, leading to a vacuum pump. `The capillary is then heated between the lines M--M and N-N in Figure 9 until the quartz is .sufficiently softthat under the vacuum it will be' collapsed upon the wire. Finally, the section including the Wire is fused off forming the unit illustratedv in Figure 3.

lThe capsule should hang in a vertical position during the collapsing operation and is preferablyl clamped in that position by meansy of a clamp about the rubber tube at a point where the capsule enters it. The heating is preferably by a hand torch and is started preferably about the line N-N and the heating progressed slowly upward to the line M-M as the lower portions of the capsules are collapsed.

By this process the unit shown in Figure 3 produced, in which the wire of Figure 2 has been completely embedded in quartz.

In order to connect the electrode or other electrical elements with the seal, one end of the seal is then fractured at about the line A--A Ain Figure 3 and removed from the end of the wire by a fracturing pressure, leaving the seal inthe form shown in Figure 4. To the seal is thenattached the velectrode indicated at 10, the

'particular electrode indicated being a cylindrical electrode and forming a part of a neon tube. The wire from this electrode is attached to the wire of a seall by a crimp joint or by spot welding. This produces the unit illustrated in Figure 5.

Then, as illustrated in Figure 6, when the seal is to be connected into the apparatus in which' it isto be used, the seal of Figure 5 with its electrode is placed within a quartz tube so that the outermost joint between the tungsten and molybdenum wires is at about l@ inch from the open end. The quartz tube is then welded to the seal by directing a small pointed flame to thepoint indicated by the arrow in Figure 6. Since the wire of the seal is entirely surrounded and enclosed by quartz at the region that this welding operation is performed, the high temperature of the welding operation is unable to vaporize the metal of the wire and accordingly the seal is preserved and the wire preserved continues vso that it is capable of acting as a conductor.

This operation produces a seal as shown in Figure 7. This seal is then marked along the line B-B and fractured and the excess removed by crushing, leaving the finished seal as shown in Figure.` In the iinished seal one end of molybdenum wire protrudes as illustrated, and can be utilized for making electrical connections.

Molybdenum does not solder readily, but a hook l can be made in the end of the wire and embedded in a drop of solder in the end of the metal cap. An optional method of connection is to spot weld a connection of Dumet wire and then to solder to the Dumet. A

While the process of making a seal herein illustrated and the seal are well adapted to carry out the objects of this invention, various modifications and changes may be made without departing from the principles and objects of the invention, and this invention includes all such changes -and modifications as come within the scope of the appended claims.

I claim:

I. A seal between a quartz envelope and an electrical lead wire comprising, a relatively fine wire of substantial length having larger wire leads connected to each end thereof, and a quartz covering completely enclosing vsaid fine wire and a portion of each of said larger wire leads.

2. An electrical quartz seal comprising, a substantial length of relatively line wire having a larger Wireattached to each end thereof, and at least partially enclosed within a quartz covering insealing engagement with the wire assembly.

3. An article of manufacture, comprising a substantial .length of relatively fine wire having a. larger vWire connected to each end thereof, and having a quartz covering surrounding and fused into intimate contact with the entire length of said fine wire and a portion of the length of each of said larger wires.

4. A seal between a quartz envelope and an electrical lead-in wire comprising a substantial length lof relatively fine wire having a melting and completely surrounding the ne wire and a larger wires.

portionof each of said ELLISO. ERICKSON. 

